Funds To Shut Nuclear Plants Fall Short

While companies ask for extensions for other reasons — primarily to keep producing power and making money — some companies have explicitly told shareholders they will use license extensions to meet their decommissioning obligations.

—Some plants are calculating growth projections for their investments with an annual return of 6 percent. While that is roughly what leading market indexes make over decades, the NRC found plant owners lost an average of 13 percent over the past two years.

In Texas, state rules govern utilities' investments, said Ashley Monts, a spokeswoman for Luminant Corp., which owns two nuclear plants near Glen Rose, Texas. Five years before a plant is set to close, she said, Luminant is required to have 60 percent of the cost available. Two and a half years out, the gap must be completely closed.

Luminant has about $385 million set aside to close its two plants in 2030 and 2033. Two years ago, that figure was $439 million. The cost of decommissioning the reactors is $824 million, almost $90 million than was estimated before.

—Plant operators appear to benefit from NRC rules that don't require them to set aside money to store old nuclear fuel, demolish buildings, or return the plant sites to pristine states. Although some states require a full site restoration, the federal government does not.